YouTube has come to define the era of online video, so let's take a look at its most popular videos of all time. Our latest update has Justin Bieber still at number one with Baby, which was the first video to earn a half a billion views! Currently, Bieber and Eminem between them make almost half of the top 10. Also of note is a music video by Jennifer Lopez called On The Floor ft. Pitbull, which has risen to number two with 400 million views in only nine months.

We first did this list in August 2007, at which point Evolution of Dance by comedian Judson Laipply was number one with nearly 56 million views (it's now outside the top 10). The next update was September 2008, when Avril Lavigne's Girlfriend pop music video was number one with 103 million views. In January 2010, Charlie bit my finger - again ! was number one, with 148 million views. By the beginning of January 2011, Justin Bieber was at number one with over 400 million views for Baby.

Here is the top ten, as of January 2012: